Engine Configurations for Snowmobiles

Abstract

A snowmobile includes a forward frame assembly defining an engine bay. An engine is positioned within the engine bay. The engine has a plurality of intake ports positioned on an aft side of the engine and a plurality of exhaust ports positioned on a forward side of the engine. An air intake system has at least one air inlet and a plurality of air outlets. The air intake system is coupled to the aft side of the engine such that each of the air outlets is configured to provide air to one of the intake ports. An exhaust system has a plurality of exhaust inlets and at least one exhaust outlet. The exhaust system is coupled to the forward side of the engine such that each of the exhaust inlets is configured to receive exhaust from one of the exhaust ports.

What is claimed is: 
     
         1 . A snowmobile comprising:
 a forward frame assembly defining an engine bay;   an engine positioned within the engine bay, the engine having a plurality of intake ports positioned on an aft side of the engine and a plurality of exhaust ports positioned on a forward side of the engine;   an air intake system having at least one air inlet and a plurality of air outlets, the air intake system coupled to the aft side of the engine such that each of the air outlets is configured to provide air to one of the intake ports; and   an exhaust system having a plurality of exhaust inlets and at least one exhaust outlet, the exhaust system coupled to the forward side of the engine such that each of the exhaust inlets is configured to receive exhaust from one of the exhaust ports.   
     
     
         2 . The snowmobile as recited in  claim 1  wherein, the engine is a four-stroke engine. 
     
     
         3 . The snowmobile as recited in  claim 1  wherein, the air intake system further comprises an airbox positioned at least partially forward of the engine bay, the airbox includes the at least one air inlet; and
 wherein, the at least one air inlet is positioned outboard of the engine bay. 
 
     
     
         4 . The snowmobile as recited in  claim 3  wherein, the air intake system further comprises an air plenum positioned on top of the engine. 
     
     
         5 . The snowmobile as recited in  claim 4  wherein, the air plenum is positioned at least partially within the engine bay. 
     
     
         6 . The snowmobile as recited in  claim 4  wherein, the air intake system further comprises a throttle valve assembly coupled to the air plenum, the throttle valve assembly positioned outboard of the engine bay. 
     
     
         7 . The snowmobile as recited in  claim 6  wherein, the throttle valve assembly is positioned below the at least one air inlet. 
     
     
         8 . The snowmobile as recited in  claim 6  wherein, the air intake system further comprises an air duct coupled between the airbox and the throttle valve assembly, the air duct routed forward and outboard of the forward frame assembly. 
     
     
         9 . The snowmobile as recited in  claim 6  wherein, the air intake system further comprises an air runner assembly coupled between the air plenum and the aft side of the engine, the air runner assembly includes the plurality of air outlets; and
 wherein, the air runner assembly extends aftward and downward from the air plenum. 
 
     
     
         10 . The snowmobile as recited in  claim 1  wherein, the exhaust system further comprises an exhaust manifold coupled to the forward side of the engine, the exhaust manifold includes the exhaust inlets. 
     
     
         11 . The snowmobile as recited in  claim 10  wherein, the exhaust system further comprises a muffler positioned outboard of the engine bay. 
     
     
         12 . The snowmobile as recited in  claim 1  wherein, the air intake system further comprises a throttle valve assembly positioned outboard of the engine bay on a first side of the engine; and
 wherein, the exhaust system further comprises a muffler positioned outboard of the engine bay on a second side of the engine that is opposite the first side of the engine. 
 
     
     
         13 . A snowmobile comprising:
 a forward frame assembly defining an engine bay;   an engine positioned within the engine bay, the engine having a plurality of intake ports positioned on an aft side of the engine and a plurality of exhaust ports positioned on a forward side of the engine;   an air intake system coupled to the aft side of the engine, the air intake system includes an airbox having an air inlet that is positioned outboard of the engine bay, an air plenum positioned on top of the engine, a throttle valve assembly coupled between the airbox and the air plenum, the throttle valve assembly positioned outboard of the engine bay on a first side of the engine and an air runner assembly coupled between the air plenum and the engine, the air runner assembly including a plurality of air outlets each of which is configured to provide air to one of the intake ports; and   an exhaust system coupled to the forward side of the engine, the exhaust system including an exhaust manifold having a plurality of exhaust inlets each of which is configured to receive exhaust from one of the exhaust ports and a muffler including an exhaust outlet positioned outboard of the engine bay on a second side of the engine that is opposite of the first side;   wherein, each of the engine, the air plenum, the air runner assembly and the exhaust manifold is at least partially disposed within the engine bay.   
     
     
         14 . The snowmobile as recited in  claim 13  wherein, the throttle valve assembly is positioned below the air inlet. 
     
     
         15 . The snowmobile as recited in  claim 13  wherein, the air runner assembly extends aftward and downward from the air plenum. 
     
     
         16 . The snowmobile as recited in  claim 13  wherein, the engine is tilted aftward such that an upper portion of the engine is aft of a lower portion of the engine. 
     
     
         17 . The snowmobile as recited in  claim 13  further comprising a heat exchanger coupled to the forward frame assembly forward of the engine. 
     
     
         18 . The snowmobile as recited in  claim 17  wherein, the heat exchanger is tilted forward such that an upper portion of the heat exchanger is forward of a lower portion of the heat exchanger. 
     
     
         19 . The snowmobile as recited in  claim 17  wherein, at least a portion of the exhaust manifold is positioned between the heat exchanger and the engine. 
     
     
         20 . The snowmobile as recited in  claim 17  wherein, the muffler is positioned aft of the heat exchanger.